// List the exports of a game module with their VAs (at the module's
// preferred base, as in Ghidra). The game DLLs export most of their C++
// classes with decorated names, so this is a quick index of what is where.
//
//   node tools/exports.mjs <module> [regex]       exports whose name matches
//   node tools/exports.mjs <module> 0x10018c60    the export at (or before) a VA
//
// Output: "va  name", sorted by name (by address for a VA lookup).

import { readFileSync } from "node:fs";

const [modulePath, query] = process.argv.slice(2);
if (!modulePath) {
  console.error("usage: node exports.mjs <module> [regex | 0xVA]");
  process.exit(1);
}

const file = readFileSync(modulePath);
const peOffset = file.readUInt32LE(0x3c);
const sectionCount = file.readUInt16LE(peOffset + 6);
const optionalSize = file.readUInt16LE(peOffset + 20);
const optional = peOffset + 24;
const imageBase = file.readUInt32LE(optional + 28);
const sectionTable = optional + optionalSize;

function fileOffset(rva) {
  for (let i = 0; i < sectionCount; i++) {
    const s = sectionTable + 40 * i;
    const virtualSize = file.readUInt32LE(s + 8);
    const virtualAddress = file.readUInt32LE(s + 12);
    const rawOffset = file.readUInt32LE(s + 20);
    if (rva >= virtualAddress && rva < virtualAddress + Math.max(virtualSize, file.readUInt32LE(s + 16))) {
      return rawOffset + rva - virtualAddress;
    }
  }
  throw new Error(`rva 0x${rva.toString(16)} is not in a section`);
}

const exportRva = file.readUInt32LE(optional + 96);
if (!exportRva) {
  console.error("no export table");
  process.exit(1);
}
const dir = fileOffset(exportRva);
const functionCount = file.readUInt32LE(dir + 20);
const nameCount = file.readUInt32LE(dir + 24);
const functions = fileOffset(file.readUInt32LE(dir + 28));
const names = fileOffset(file.readUInt32LE(dir + 32));
const ordinals = fileOffset(file.readUInt32LE(dir + 36));

const exports = [];
for (let i = 0; i < nameCount && functionCount; i++) {
  const nameOffset = fileOffset(file.readUInt32LE(names + 4 * i));
  const end = file.indexOf(0, nameOffset);
  const name = file.toString("latin1", nameOffset, end);
  const ordinal = file.readUInt16LE(ordinals + 2 * i);
  const va = imageBase + file.readUInt32LE(functions + 4 * ordinal);
  exports.push({ va, name });
}

const hex = (va) => va.toString(16).padStart(8, "0");
let shown;
if (query && /^0x[0-9a-f]+$/i.test(query)) {
  const va = Number.parseInt(query, 16);
  const before = exports.filter((e) => e.va <= va).sort((a, b) => b.va - a.va);
  shown = before.length ? exports.filter((e) => e.va === before[0].va) : [];
} else {
  const pattern = query ? new RegExp(query.replace(/^\/|\/$/g, ""), "i") : null;
  shown = exports.filter((e) => !pattern || pattern.test(e.name)).sort((a, b) => a.name.localeCompare(b.name));
}
for (const e of shown) {
  console.log(`${hex(e.va)}  ${e.name}`);
}